A Brief Description on Network
Network,as a result of the combination of modern communication technique and computer technology, it has powerful functions. It can communicate information among different network equipment,information covers variety of messages including words,letters,news,pictures,etc. And rich resources can be shared through network,like software,hardware,as well as information. Further network can balance the load of the computer. Through network,multiple computers can work together to enhance the real-time performance of solving problems and find better ways to handle complicated issues.
According to the coverage range of network,it can be divided into LAN(Local Area Network) and WAN(Wide Area Network). WAN covers a wide range like a country or a continent. The purpose is to make each LAN dispersed in a large area interlinked. There’s no doubt that Internet is a typical WAN. On the contrary,LAN refers to a communication network in a small region,usually within the range of kilometers. For example,a room,a building,or a campus. There are some essential devices for LAN:
– Computer including PC,web server,etc.
– Transmission media(coaxial cable,twisted pair,fiber optic cable and so on)
– Network adapter
– Various devices for connecting computer and transmission media,like HUB.
– Software system
There is a language applied in all computers interlinked via network,this is called network protocol. Just unified network protocol can make sure the smooth communication between different computers. In order to exchange data in an organized way in computer network,each node must comply with some agreed standards and rules. These standards and rules developed for network data exchange are defined network protocols. Many kinds of protocols can be chosen and applied depending on specific situation. For example,computers on Internet use TCP/IP model.
Network Interconnection
OSI is the Open Systems Interconnection developed by ISO. Follow OSI standard,a system can connect other systems following OSI standard as well anywhere in the world. It defines the standard frame linking different computers. OSI model contains physical layer,data link layer,network layer,transport layer,session layer,presentation layer,and application layer.
TCP/IP
In practical use,there’s no specific protocol fully complying with OSI,however they can correspond to OSI. At present,TCP/IP is the most widely used protocol. In general,TCP offers transport service,while IP provides network layer service.
OSI Reference Model TCP/IP Reference Model
Ethernet
Ethernet is currently the most common communication protocol standard adopted by existing LAN.
Features contain,
– Share media: all network devices use the same communication medium in turn;
– Broadcast domain: a collection of all devices which can receive the same broadcast message.
– CSMD/CD: prevent more nodes from transmitting simultaneously
How does Ethernet work when a host needs to transmit data？
Step 1: detect whether there is a signal on the channel or not. If there’s a signal,then the channel is busy and keep detecting.
Step 2: If there’s no signal,data can be transmitted.
Step 3: Meantime keep detecting when transmitting,if a collision occurs,please stop the transmission.
Step 4: Wait a while and re-execute step 1
Step 5: If no collision is found,the transmission is successful. Computer returns to signal channel detection.
Broadcast Ethernet links all computers via HUB. For data package,computer receives it uploaded by Ethernet first; next it compares IP address of data package with its own IP address,if they are matching,data package will be further processed;otherwise it will be abandoned.
Our ID551PN weighing controller can connect 4 scales at the same time. In the picture it connected 4 material tanks,all information can be transmitted to computer or PLC via Ethernet.
Our products with Ethernet include ID226 weighing terminal,ID510 weighing controller,ID511 weighing controller,ID551PN weighing controller. There are general Ethernet and Industrial Ethernet used with weighing terminal. Users need to pay attention to their differences,therefore weighing terminal with proper Ethernet can work efficiently in practical application.
Two or more computer networks are interconnected,using network communication equipment,to make up a larger network system, this is network interconnection technology. There are different layers in network interconnection. In OSI model,network communication depends on different layer,and equivalent layers can communicate with each other. Interconnection with more layers,the interconnected devices are more complicated. The equipment contains repeater,network bridge,router,gateway and so on.
this picture shows network equipment and connection:
Ethernet primarily covers TCP/IP,EtherNet/IP and Modbus TCP. They have the same shape in interface,but the internal protocols of interfaces are different. TCP/IP is general Ethernet,however EtherNet/IP and Modbus TCP are industrial Ethernet and they have stronger ability of anti-interference than TCP/IP.